Electric heateb



Oct. 1; 1929.

w. E. GUEST ELECTRIC HEATER Filed Sept. 10, 1926 Mg GMT;

Patented Oct. 1, 1929 UNETEB STATES WARD EARL GUEST, OF CHICAGO, ILLINOIS ELECTRIC HEATER Application filed September 10, 1926. Serial No. 134,604.

This invent-ion relates in general to electric heaters and refers more particularly to a portable electric heater from which the heat is caused to emanate by means of convection currents generated as distinguished from heat radiated.

An object of this invention is to device a portable electric heater in which the desired hating is effected through the agency of convection currents created bythe heater with a minimum amount of heating by radiation.

It is a further object of this invention to provide an improved means for controlling the temperature within a room to be heated by means of a control unit located within the heater.

Another object is to provide an improved heater of this type comprising a hollow case or flue having therein a heating unit located to provide the most efficient generatioirof convection currents, the heating unit being removably secured in the heater case; and in which the arrangement of the parts is such as to insure a high degree of safety.

Other objects and advantages will become apparent in the following description and from the accompanying drawings, in which:

Figure 1 is a vertical section of the heater taken on the line l1 of Fig. 2.

Fig. 2 is a front elevation of the heater.

Fig. 3 is an enlarged fragmentary view of one form of control means.

Fig. 4 is a sectional view taken on a line 44 of Fig. 2.

In attaining the objects of this Invention I provide an upright box-like heater case or flue 5 which has an air outlet at the upper end which may be provided by having one faceG partially open. The flue 5 also has an air inlet provided by leaving the lower end open. A curved wall or diverter 7 is secured to the entirely closed face 8 of the flue intermediate the upper and lower ends thereof, and slopes forwardly to join the front face near the upper edge of the opening therein. A grille 9 serves as a screen for the opening in the face 6. A handle 10 of any suitable construction may be provided to facilitate movement of the case from one position to another.

In the open lower end of the caseis mounted a removable electrictheatin g unit designated generally as 11, properly arranged to direct the heat therefrom in an upward direction. The heating unit may be of any suitable construction, but I have devised a unit which is very simple inconstruction and is exceedingly efficient in operation. The supporting frame for this unit comprises a pair of side members 12 and a pair of end members 13 rigidly secured togetheras by bolts 14. to provide a substantially rectangular open-faced frame adapted to fit snugly into the open end of the case 5 and to be removably securcd'therein in asuitablemanner as in the present instance by means of set screws '15 mounted in the case to engage the frameof the heating unit. The side members '12 have their edges turned to provide an inwardly opening channel and each turned edge is, at appropriate intervals, struck inwardly of the channel at two adjoining places, thereby providing a series of clips 16 integral with the side members 12. i

A heating element 17 formed in the usual manner of coiled high resistance wire is wound alternately between the two ends13 of the frame, which are insulated in a suitable manner as by mica sheets to prevent contact of the heating elementwith the end members. A plurality of insulating supporting plates 18 of sheet mica or other substantially heavy insulating material, extend transverselyof the frames and are held in place by means of the clips 16 on the side members 12. The heating element is threaded through 'appropriate openings in these plates which thus serve to support and to space the heating element. A downwardly extending insulated plate 19, on one end member, has thereon a pair of terminal binding posts 20 which extend outwardly through the plate to provide contact members 21 arranged to fit into a commercial type of connection plug 22.

This construction provides a simple, sturdy heating unit, in which all of the parts are self-contained and which may be bodily remove-d from the heater for repairs or replacement.

An essential feature of this invention resides in the operating principle. The prior types of electric heaters utilize generally the principle of radiant heat. That is, the heat emanates in all directions from a source of heat and by means of reflection is directed along a certain path. Oftentimes such a concentration of heat rays in one direction is objectionable because these concentrated rays have been found to scorch or burn objects located a considerable distance away. Furthermore, direction of the heat rays in this manner does not properly diffuse the heat throughout a room.

In my heater the heat rays are used as much as possible to create convection currents by drawing cool air in at the base of the heater and heating that air, such air then passing upwardly in the heater until de-,

fiected outwardly through the grille 9 by the curved portion 7 on the wall 8. The creation of convection currents in the room causes a much more rapid heating thereof than is obtained by a purely radiant type heater.

The utilization of the principle of convection currents in my heater has enabled me to provide the heater with a relatively accurate automatically operating thermostatic control which is incorporated in the heater. The thermostatic control may coinprise any well known type of thermostat. In the present instance I have shown installed a simple circular bi-metallic thermostat strip 24 whichis set to expand and break a circuit at a certain predetermined temperature. The thermostat 23 is securely mounted within the case 5 at a point above the heating unit 11 and a lead 25 from one of the binding posts 21 to one end of the heating unit 17 is connected in series with the thermostat strip 24 (see Fig. 3). Thus the bi-metallic strip upon being-subjected to a certain degree of heat will expand, moving one contact 26 away from the other insulated contact 27 to break the circuit. Experimental tests determine to what degree of heat the thermostat must be exposed in order to correspond to a desired degree of heat in a room and the thermostat is then set to open at that temperature. Thus the thermostat can be set at a certain temperature, and when, during operation, the temperature of the air within the heater case has built up to a certain limit, the thermostat will automatically shut elf the heater. This control system in itself provides a safety devicein case a coat, wrap or other inflammable obstacle be thrown over the heater outlet accidentally. In this event the entrapped air within the heater case is heated very rapidly and in a very short time will cause the disconnecting operation of the thermostat.

Although the invention is susceptible of va rious modifications and alternative constructions, I have shown and herein described in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the invention to the specific form disclosed, but intend to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

I claim as my invention:

1. A portable electric heater having, in combination, a heater case, a removable heat ing unit including a heating element arranged to extend across the lower end of said case, contact means on said unit connected with said. heating element for connection of said element with a source of current, and thermostatic control means secured within said heater case and interposed in a circuit between said contact means and said heating element whereby when the temperatureywithin the heater case reaches a predetermined point, said thermostatic control means will operate to break the circuit to said heating element.

2. A portable electric heater comprising, in combination, a heater case having a partially open front face, an open lower end, and a back, a diverter secured to said back and arranged to slope forwardly to meet the upper end of said open face, a heating unit removably secured in said case, and a heating element carried by said unit and extending in a substantially horizontal plane across and adjacent the open lower end of said case when said unit is secured therein.

3. A portable electric air heater comprising, in combination, a top wall and side walls defining a heating space, legs on said side walls to space the heater from the surface upon which it is supported whereby to give access of air into said heating space, the lower edges of the side walls defining an inlet opening, an aperture in one of the side walls pro viding an outlet opening, a plurality of heating coils extending substantially horizontally across said inlet opening and vertically positioned insulating plates spanning said opening and supporting said coils.

In testimony whereof, I have hereunto affixed my signature.

IVARD EARL GUEST. 

